Tecnifibre X-One Biphase 1.18 String Red

A premium multifilament string, X-One BiPhase 1.18
delivers superb comfort, feel and a crisp response. A good
choice for players seeking an arm-friendly string without
sacrificing power. Provides good tension maintenance, too.
About as gut-like as synthetics get. Offers a livelier feel with less
durability compared to the thicker gauge versions. A great choice
to liven up a tight string pattern.

According to Tecnifibre,
"the X-One Biphase string uses High Heat Capacity (H2C) fibers
which allows the use of an innovative chemical treatment process
called Trimerization. This new process increases the cohesion
between chemical molecule links through extreme variations in
temperature to result in ultimate dynamic efficiency (power) and
exceptional feel. The new patented Biphasic process, with its
visible marks on the string, extends string life by 20% and offers
increased spin. Similar to its leading string, NRG2, the
multifilament fibers within this string are immersed in
polyurethane to provide shock absorption and optimum
comfort."